Orbicular granite
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Orbicular granite is an uncommon plutonic rock type which is usually granitic in composition. These rocks have a unique appearance due to orbicules - concentrically layered, spheroidal structures, pro
Outcrop of orbicular granite near Caldera, Chile.
Close-up of orbicular granite near Caldera, Chile.
Polished rock sample of orbicular granite from Mount Magnet, Western Australia
Feldspar
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Feldspar is a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the
Specimen of rare plumbian (lead-rich) feldspar
Crystallized white feldspar, with an upright 4 cm aquamarine crystal perched on it
Feldspar and moonstone, from Sonora, Mexico
A cluster of euhedral feldspar crystals with a schorl crystal